Spirobranchus sp. (probably S. corniculatus)
Common Names: Christmas Tree Worm
Range: Tropical Indo-West Pacific and the Red Sea
Natural Environment: As for the specimens shown, the branched, tentacled crowns have two spirals each, which collect food in the form of suspended particulate organic matter and phytoplankton.
Water Requirements: Calcium 380 to 430 mg/l, alkalinity 2.5 to 3.0 meq/l, pH 8.1 to 8.2, specific gravity 1.025, phosphate < .015 mg/l, and a temperature range of 76° to 83°F (24 to 28°C).
Based on the shape and size of my specimen’s operculum (a protective lid used when the worm retracts into coral), I believe it comes from the Indo-Pacific.
Christmas tree worms require bright light and swift water movement in aquaria. Trace elements and other liquid-based phytoplankton products made especially to enhance the nutrition of filter-feeding animals should also be used per manufacturer instructions.
Tankmates that will pick on or eat tubeworms, such as triggerfishes, angelfishes, pufferfishes, butterflyfishes, crabs, peppermint shrimp, etc., should not be housed with Christmas tree worms.
It has been quite common in the past to show these worms living in a head of Porites coral and label them as S. giganteus. Nevertheless, that species only originates in the tropical Western Atlantic and Caribbean. It’s obvious that it is difficult to determine the species in the genus Spirobranchus.
To shed light on this confusing aspect, I turned to the British marine biologist and diver Vincent B. Hargreaves, PhD, who has his doctorate in marine biology with a double major in ichthyology and marine invertebrate zoology, for his help in clarifying the present situation.
Broadly speaking, as he describes it, there are three groups or complexes of Christmas tree worms.
He recognizes three species in the giganteus complex: S. incrassatus (Panama), S. spinosus (Subtropical coastlines of southern California/Mexico), and S. giganteus (Tropical Western Atlantic/Caribbean).
In the S. corniculatus complex are five species from the Indo-West Pacific and western Indian Ocean: S. corniculatus, S. gaymardi, S. paumotanus, S. nigranucha, and S. gardineri.
The species in the S. tetraceros complex have distinct differences from the S. giganteus complex, as their trees develop on a separate stem from the operculum. Also, they do not form a close arrangement with stony corals, as they may be found on/in any type of calcium carbonate coral rubble. This group’s species have not been separated out yet, but H. A. ten Hove has laid down the basics of the current understanding of the serpulinae group.